首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   838篇
  免费   68篇
  国内免费   8篇
电工技术   27篇
综合类   7篇
化学工业   198篇
金属工艺   32篇
机械仪表   41篇
建筑科学   27篇
矿业工程   8篇
能源动力   29篇
轻工业   80篇
水利工程   23篇
石油天然气   20篇
无线电   94篇
一般工业技术   105篇
冶金工业   37篇
原子能技术   3篇
自动化技术   183篇
  2024年   3篇
  2023年   12篇
  2022年   28篇
  2021年   56篇
  2020年   65篇
  2019年   62篇
  2018年   86篇
  2017年   80篇
  2016年   69篇
  2015年   32篇
  2014年   61篇
  2013年   101篇
  2012年   69篇
  2011年   53篇
  2010年   43篇
  2009年   33篇
  2008年   24篇
  2007年   13篇
  2006年   7篇
  2005年   1篇
  2004年   4篇
  2003年   2篇
  2002年   1篇
  2001年   1篇
  1998年   1篇
  1991年   1篇
  1990年   1篇
  1989年   2篇
  1978年   1篇
  1977年   2篇
排序方式: 共有914条查询结果,搜索用时 93 毫秒
101.
HIGHT is a lightweight block cipher introduced in CHES 2006 by Hong et al as a block cipher suitable for low‐resource applications. In this paper, we propose improved impossible differential and biclique attacks on HIGHT block cipher both exploiting the permutation‐based property of the cipher's key schedule algorithm as well as its low diffusion. For impossible differential attack, we found a new 17‐round impossible differential characteristic that enables us to propose a new 27‐round impossible differential attack. The total time complexity of the attack is 2120.4 where an amount of 259.3 chosen plaintext‐ciphertext pairs and 2107.4 memory are required. We also instantiate a new biclique cryptanalysis of HIGHT, which is based on the new idea of splitting each of the forward and backward keys into 2 parts where the computations associated to each one are performed independently. The time complexity and data complexity of this attack are 2125.7 and 242, respectively. To the best of our knowledge, this is the fastest biclique attack on full‐round HIGHT.  相似文献   
102.
Metallurgical and Materials Transactions A - The effects of cold rolling and the subsequent annealing were studied for the AISI 309Si stainless steel. During annealing of cold-rolled sheets, the...  相似文献   
103.
Telecommunication Systems - This paper analyzes the carrier-to-interference ratio (CIR) of the so-called shotgun cellular systems (SCSs) in $$\tau $$ dimensions ( $$\tau =1, 2,$$ and 3). SCSs are...  相似文献   
104.
Accurate estimation of rainfall has an important role in the optimal water resources management, as well as hydrological and climatological studies. In the present study, two novel types of hybrid models, namely gene expression programming-autoregressive conditional heteroscedasticity (GEP-ARCH) and artificial neural networks-autoregressive conditional heteroscedasticity (ANN-ARCH) are introduced to estimate monthly rainfall time series. To fulfill this purpose, five stations with various climatic conditions were selected in Iran. The lagged monthly rainfall data was utilized to develop the different GEP and ANN scenarios. The performance of proposed hybrid models was compared to the GEP and ANN models using root mean square error (RMSE) and coefficient of determination (R2). The results show that the proposed GEP-ARCH and ANN-ARCH models give a much better performance than the GEP and ANN in all of the studied stations with various climates. Furthermore, the ANN-ARCH model generally presents better performance in comparison with the GEP-ARCH model.  相似文献   
105.
Fatigue crack growth(FCG)tests were conducted on a medium-Mn steel annealed at two intercritical annealing temperatures,resulting in different austenite(γ)to ferrite(α)phase fractions and different γ(meta-)stabilities.Novel in-situ hydrogen plasma charging was combined with in-situ cyclic loading in an environmental scanning electron microscope(ESEM).The in-situ hydrogen plasma charging increased the fatigue crack growth rate(FCGR)by up to two times in comparison with the reference tests in vacuum.Fractographic investigations showed a brittle-like crack growth or boundary cracking manner in the hydrogen environment while a ductile transgranular manner in vacuum.For both materials,the plastic deformation zone showed a reduced size along the hydrogen-influenced fracture path in comparison with that in vacuum.The difference in the hydrogen-assisted FCG of the medium-Mn steel with different microstructures was explained in terms of phase fraction,phase stability,yielding strength and hydrogen distribution.This refined study can help to understand the FCG mechanism without or with hydrogen under in-situ hydrogen charging conditions and can provide some insights from the applications point of view.  相似文献   
106.
In this study, undoped and nano Fe doped SnO2 nanostructures were synthesized by hydrothermal method. Characterization of the synthesized nanostructures was performed by X-ray diffraction and scanning electron microscopy. For investigation of optical properties, photo luminescence and UV–Vis spectrum were taken. The electrochemical response of the carbon paste electrode modified with synthesized nanostructures toward levodopa (L-Dopa) was studied. Cyclic voltammetry studies using prepared modified electrodes showed outstanding electrocatalytic properties towards electro-oxidation of L-Dopa and a significant reduction was observed in anodic over voltage compared to the bare electrode. Obtained results indicated the effective role of the employed dopant. Best response in terms of the current enhancement, overvoltage reduction, and reversibility improvement of the L-Dopa oxidation reaction under experimental conditions was obtained by modified electrode with Fe doped SnO2 nanoparticles.  相似文献   
107.
The inter-diffusion of segregating elements (Nb, Mo, and Ti) in the cast ingot of Inconel 718 superalloy during homogenisation at elevated temperature was studied by a new model based on the characteristic diffusion length. The proposed simple method was used for obtaining the homogenisation time required for back-diffusion of each element. Therefore, the developed model can be used for both studying the diffusion of alloying elements and estimation of homogenisation time, where the latter is important from the industrial standpoint.  相似文献   
108.
Pattern Analysis and Applications - One subject that has been considered less is a binary classification on data streams with concept drifting in which only information of one class (target class)...  相似文献   
109.
Wireless Personal Communications - One of the important objectives of underwater acoustic sensor network is to extend the lifespan of a network which depends on the topology control mechanisms....  相似文献   
110.
Nowadays, most fingerprint sensors capture partial fingerprint images. Incomplete, fragmentary, or partial fingerprint identification in large databases is an attractive research topic and is remained as an important and challenging problem. Accordingly, conventional fingerprint identification systems are not capable of providing convincing results. To overcome this problem, we need a fast and accurate identification strategy. In this context, fingerprint indexing is commonly used to speed up the identification process. This paper proposes a robust and fast identification system that combines two indexing algorithms. One of the indexing algorithms uses minutiae triplets, and the other uses orientation field (OF) to index and retrieve fingerprints. Furthermore, the proposal uses some partial fingerprint matching methods on final candidate list obtained from the indexing stage. The proposal is evaluated over two national institutes of standards and technology (NIST) datasets and four fingerprint verification competition (FVC) datasets leading to low identification times with no accuracy loss.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号